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Author Topic: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni  (Read 7915 times)

Jack D

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Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« on: January 09, 2014, 12:49:46 am »

Hi everyone.

I'm in the process of converting a long fo'c'sle Flower class corvette into a late war short Fo'c'sle vessel. Essentially it boils down to a complete tear down back to the hull and rebuild virtually from scratch, with only some pieces of original superstructure remaining.
I didn't start the refit, I got the boat after a considerable amount of work had been completed by Unbuiltnautilus, so many thanks go to him for doing a great job of the 'scary stuff' like putting the deck on and reshaping the bow.

This is my first ever scratchbuild, so the end product probably isn't going to be amazing but I am going to try and add as much detail as my (limited) skill allows.
The original plan was (and still is) to build this corvette as a late war Canadian vessel which retained the short forecastle but gained features of the more modern corvettes, like the repositioning of the mast, installation of the Type 271 radar and the addition of more anti-aircraft weaponry. To this end, the ship this model will be based on will be the HMCS Alberini, although it may not be a perfect copy and may include some common modifications to Flower class Corvettes which weren't necessarily on the Alberini herself.

Now, onto the build. The first section of these photos were taken by Unbuiltnautilus detailing the initial tear down and re-build.

This is a photo of the model prior to refit. She has HMS Crocus' pennant number on the ship itself and name on the stand, although interestingly the camouflage pattern is that of HMS Bluebell. The model has seen several owners and undergone a number of refits in the past. There was some paint based archeology going on during the refit but we'll get to that later.

The original deck fittings were torn up to expose the wooden deck. I am hoping to finish the build with new wooden decks installed on the ship where it was located on the real vessels.

The main deck has been ripped up and the forecastle has had a large part lopped off to shape the shorter version present on the early British corvettes before refit and some Canadian vessels throughout the war.

Fitting the main drive battery into the hull prior to tray construction in the hull. The battery is a monstrous 12v 12aH gel battery which combined with the Graupner 720BB motor gives this model exceptionally long sea legs.
 
 
 
 
 
 
 
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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #1 on: January 09, 2014, 02:55:03 pm »


The deck of the forecastle is removed ready to be replaced like the rest of the decks.

The corvette has the new forecastle deckmocked up and supports for the main deck are starting to go in. The original superstructure is mocked up as how the corvette will eventually look.


The supporting structure for the main deck is going in and beneath you can see the wooden bottom added, providing slots for the motor and battery to rest in. It's possible that I will extend this decking towards the bow providing room for a second battery- this boat needs a lot of ballast and will eventually have a lot of extra features like lights, smoke etc which may warrant a second power supply, alongside the obvious advantage of easily removable ballast.


Here is the finished deck support at the stern and the supports being installed at the very side of the hull which will help to make a waterproof seal between the hull and the deck.

The new deck laid down and ready for access to be cut to get to the RC bay.

Holes have been cut in the new deck to get access down below. Note at the front where the hole widens- this is because the 12Ah battery is wider than the original superstructure- this results in the first non-historic modification with the superstructure at the front widening slightly.

Here you can see that four copper tubes have been installed at the stern. These will allow cables to be run out to pyrotechnic 'depth charges' trailing behind the ship for use in convoy escort displays. this is the first of the display focused modifications to the model.

The new deck on the forecastle has ridden up slightly while it was setting, resulting in a gap between the hull and the new deck.

This gap was filled and the prow shaped properly with filler. Additionally, copper tubing was run through the bow to make a hawsepipe to eventually allow realistic suspended anchors. the angle of the deck wasn't correct after the rebuild, so the plasticard you can see is a guide for further reconstruction of the bow.

The new bow made up with fibreglass sheet on the top and at the correct angle. Combing has also been added around the access to the hull- as high as the superstructure to make sure the superstructure will not fall off or let in water in rough weather.

This marks the end of the work done by Unbuiltnautilus on this project and I took over the build from here. Again I'd like to praise the high build quality and soaring me from having to construct a deck from scratch on my first proper model (although I'm sure I'll become acquainted how to on my next build).
 
 
 
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unbuiltnautilus

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #2 on: January 09, 2014, 03:12:50 pm »

This is how all models should be built, hammers, grinders, and much brutality :-) , but, honestly, enjoy the build and i am glad the model went to a good home, even after I destroyed it!!
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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #3 on: January 09, 2014, 03:40:01 pm »


This is the first float test to get ballasting correct and make sure there are no leaks in the hull. There is still no forward superstructure and the old bridge and funnel section are the only things covering the hole. At this point a perspex sheet has been mounted on four lengths of studding to hold the RC equipment, with the aim that its' height can be adjustable and a second set of control equipment (such as pyrotechnic controls), could be easily removable from the boat outside of display season. However, I didn't check to see if the studding could move while it was setting and the whole assembly shifted so the perspex deck is no longer removable. The whole thing will be removed and rebuilt at a later date.

This is the corvette at the Chichester Canal endurance run earlier this year. Due to the final year of university, I haven't had a lot of time to work on the boat, but between the last picture and this one superstructure has been built to cover the access for to the hull and a plate added over the rudder access hole. The bandstand has been moved to the very back of the superstructure and the stern has been heated by a hot air gun and flattened to better resemble the flat Canadian style.
At the bow the protruding copper piping has been cut off and covers reducing the diameter of the holes introduced, along with detail work building up the mounting for the winch. The winch itself seen here will be replaced.

In preparation for more extensive work on the deck (installing the turret, a new winch etc), the hull is being stripped for repainting before work on the top commences. This is where it became evident that the ship has had numerous refits. The paint is a pain to remove- I can't simply sand it down for fear of destroying surface details like portholes and the individual plates of the hull and products like Mr Muscle and Fairy Powerspray didn't cut it. Eventually I started using Modelstrip. While it takes much longer to apply than the others it does work rather well.
Unfortunately, there were several layers of paint under the first one. The photo above is of the starboard side after the first layer of paint was removed, revealing what appears to be an arctic camouflage pattern. If anyone knows the exact ship I would be interested to know which one it was.
also alongside the deeper layers of paint were vinyl lettering for the pennanat number of HMS Bluebell. These letters were under so much paint you couldn't tell they were there on the initial model.
Also note the extra wash ports cut into the hull where the extended forecastle used to be. These are still rough and will be neatened up after the hull stripping is complete.
In addition you can see the bilge keels added to the hull by Unbuiltnautilus- typical of Canadian corvettes the bilge keels extend futher from the hull but are shorter than those on their British counterparts.


Paste and clingfilm are the orders of the day for stripping the hull down. It is a fairly extensive process needing two or three layers of modelstrip to get to bare fibreglass beneath. The red you can see between the modelstrip is a phenomenon where the red paint underneath is liquefying and forcing its' way past the modelstrip on top of it. This makes for some particularly gruesome scenes where it looks like the hull is literally bleeding.

Fortunately the red paint below the waterline appears to only have been applied once or twice and was probably left alone during the refits, because one coat of modelstrip is enough to get the vast majority of the paint off, leaving only small stubborn spots to be sanded off.


This is a homemade smoke generator which will be in the corvette. Based off of one of Unbuiltnautilus' designs, this uses a length of wire wrapped around an insulated core (in this case, salvaged from an old bar heater) then in turn wrapped in heatproof fibrous material which is soaked fluid which produces smoke (at the moment I am using Johnsons baby oil. This will however be replaced by commercially available smoke fluid of the kind used by indoor smoke machines because baby oil smells rather bad). Inside, the heating wire is connected to a ceramic chop-block and the cables coming out of the box are transformer wire. They are also fixed in place to prevent rubbing against the bare metal which could eventually cause a short circuit and also to prevent smoke from escaping.
The fan on top is a computer fan and the whole system will run off of a 12v battery. If you are thinking of making your own design, take note- when you force air into a contained space, like this fan and box, vortexes will be set up in the confined space which will push the smoke in directions you don't want. If you have as powerful a fan and a big hole in the box to mount it, these vortexes can become powerful enough to push most of the smoke back out through the fan rather than the pipe. In this case the smoke is still forced upwards fairly vigorously, so I might be able to get away with it without having to buy a new box and fan which are the most expensive parts of the unit.
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Sandy

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #4 on: January 10, 2014, 12:53:41 pm »

Looks great. Nice to see how other folk do their internal work.

It is a fiddly job converting to a short forecastle hull, as I found out as you have to add extra wash plates and scuttles and plans are optional.

I think the short forecastle ships look much nicer.

Here's mine:-

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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #5 on: January 10, 2014, 01:47:26 pm »

She's looking good!
I hadn't actually thought of putting wash plates in, just trying to keep water out as much as humanly possible. I'll look into it though- the only problem is pumping the water out of all of the compartments. Of course I could leave a small gap at the bottom for water to run through- small movements aren't a problem but big ones are! I'm certainly tempted to build bulkheads around the motor- she could probably sail with a good few pints in her in that case!
I did have a model sink last year because of weight shifting around inside (although that was because I didn't do my homework and used fibreglass paste to fix a battery cradle into a smooth plastic hull and it predictably sheared off when the boat rolled). So I should be motivated to prevent such a thing happening again. It would also enable the boat to be sailed in the worst of weather knowing that little water can get in and what does isn't going to cause issues.
I'm not working to specific drawings. I'm getting most of my measurements from a drawing of HMCS Alisma from early 1943 (old style bridge but with radar installed) and other photos from Warship perspectives: Flower Class Corvettes in World War Two, along with other photos of ships and models from the internet.
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TailUK

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #6 on: February 23, 2014, 03:25:01 pm »

Starting to look really good now you've got some paint on that hull.  I was intrigued by your smoke generator, don't suppose it would be possible to get a picture of the inside of it?  Thanks
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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #7 on: February 24, 2014, 03:03:40 pm »

First I'd like to apologise for mis-spelling the name of the ship I'm building the corvette into- I somehow got it into my head that it was Alberini instead of Alberni.
Only a small amount of progress to report- I finished stripping paint off of the hull with Model Strip but it left stubborn patches ofpaint which needed to be removed with sandpaper and finally a dremel tool for the parts in recesses. Owing to the terrible weather we've been having lately I haven't had much of a chance to get out into the garden and do it although it has finally been finished.

Above is a photo of the port side after the final lot of modelstrip came off, with the stubborn marks left over.

Here's the hull after dremeling- I'm not too concerned about the residual paint on the hull near the propshaft as its' unlikely to cause serious problems.
This means I can now get the Milliput out and start fixing the scarring around the new washposrts installed at the front and the depth-charge ports at the back which I made a bit of a pig's ear on along with other small deformaties in the hull to be filled and the hull can then be painted and ready for some superstructure work.

Here's a picture of the inside of the smoke generator. you can see the massive hole for the fan, which is actually far too big- a smaller fan and hole would be much more effective at driving smoke out of the correct end.
 
On the main unit itself you can see the transformer wire running from the external chop block into the unit and through the internal ceramic block (in this case the transformer wire passes through uninterrupted but the chop block adds some support). This is hooked to a piece of an old bar heater and wrapped in fire-resistant material. I believe most of the discolouring is residue from the oil being used but I'm not entirely sure. There is obviously a fairly major short circuit hazard so I'd reccomend making sure you have sufficient material to stop any part of the heating parts from coming into contact with the case (probably using more than I have here). also note that the wire on the old bar heater isn't supposed to get as hot as it was originally designed to- glowing wire is far, far too hot for this kind of machine.

 
Also bear in mind that the metal cases can get very hot, especially in smaller units (I've run this one for half an hour and it's still been cool to the touch, but the smaller one I based this off of gets hot very quickly). I'm sure everyone reading this would have guessed, but it's better to be safe than sorry.
 

Additionally, I have to point out that I in no way encourage people to try this at home and making your own smoke unit is done entirely at your own risk and I am not responsible for any damage, injury or death resulting from the use or mis-use of a similar device (you can never be too careful these days).
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triumphjon

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #8 on: February 25, 2014, 07:32:36 pm »

is the refit / transfomation going to be finished before easter monday  jack ? 
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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #9 on: February 26, 2014, 12:12:08 am »

is the refit / transfomation going to be finished before easter monday  jack ?
No, not a chance. But there's a fairly good chance it'll look like a corvette enough to make it (aleit lacking a lot of detail), but I'm not going to put money on it- especially since wiring up all the lights to the superstructure could make more problems for an already fiddly job.
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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #10 on: April 15, 2014, 10:44:34 pm »

Work has been progressing slowly but surely- the hull has had the scars made when cutting new washports and other minor issues sorted with milliput, new 'ledges' under the washports have been fitted and I've made a new hawsepipe opening to replace the one I lost in the garden (silly me!).
The hull is ready for painting bar some very minor work so the first layer of basecoat grey will be going on tomorrow.
I've also cut out all the pieces of the 'chart house' on the bridge ready for assembly and I've scratch built a watertight door for it (working to my plan it's slightly too small for a moulded fitting- There was probably actually a regular door at the back there but I can neither be sure and I wanted to give it a go).

Admittedly it's pretty awful but hopefully people won't notice it much, being tucked away.
 
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ballastanksian

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #11 on: April 16, 2014, 09:19:12 pm »

It certainly is a busy piece what with all those handles and reinfor cement detail. The main thing is you are having a go at scratch building.

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Jack D

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #12 on: April 20, 2014, 12:37:56 am »

Work is proceeding apace- the Chichester Canal run is coming up on Easter Monday and this corvette will sail there, a year after she last sailed at the Easter canal run last year. I also went to the autumn run last year, but ashamed of the state of the corvette I took another boat (which sank, was repaired and sailed for the first time again last Monday, but that's a tale for another day).
Even though she won't even be near finished, she'll look miles better than she did last year already.
 

First up, I finished preparing the hull and putting in ledges under the new washports and put the base layers on the hull. I started with the antifouling, for which I used Halfords red plastic primer.

 
 

Next up, the basic grey top. The antifouling runs in a straight line and doesn't follow the lines of the corvette, so I rigged up a piece of string as a guide for the masking. Not sure it worked perfectly, but well enough. you can also see the mew plasticard ledges and milliput patches here.

 

Here's a photo of the grey applied and after any small mistakes were corrected by hand (luckily I have an extensive collection of acrylic paints, which closely match the red and exactly match they grey). This grey is Halfords grey plastic primer. I have also had a can of Dark Admiralty Grey made up which will be used for the camouflage pattern later. She's looking better now though, finally.

 

Here's the bridge house made up and ready for spraying, complete with scratch built watertight door. this will eventually have a ladder at the back, a wooden deck on top and stanchions with spotlights up there.

 
 

As a side project to keep myself interested through long, relatively boring stretches of work I decided to paint the plastic prop to look like a weathered brass one. It's been varnished but I have no idea if it'll hold up to the stress, especially at the tip of the blades. It was only an hour's work though (with lots of waiting for it to dry!), so it was worth a go anyway.

Tomorrow is going to be a very busy day- I have to rub down the old superstructure and get it resprayed along with the rudder, build the new turret housing (although getting it motorized is highly unlikely), patch a giant hole in the crew shelter under the focsle and re install all of the electronics and the rudder before Easter Monday if she's to look halfway decent.
 
 
 
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unbuiltnautilus

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #13 on: April 24, 2014, 12:32:33 pm »

Like the prop. I didn't realise it was plastic on Monday when we de-weeded it, looked brass :-))
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Sandy

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Re: Flower Class Corvette Refit- HMS Crocus to HMCS Alberni
« Reply #14 on: April 25, 2014, 10:36:12 pm »

Looks good  :-))

I fiddled and farfed with painting mine as I realised that the Flowers sat stern low, just like the whalers they were based on, so the waterline shouldn't follow the keel line.

I built my stand so that the waterline is horizontal but the keel rises noticeably towards the bow.

This is why in photos of short fo'c'sle Flowers you can see that the bridge leans aft as the ships were built with the keel horizontal (and bridge vertical) but float trimmed by the stern.

All the best
Sandy
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